Software radios are emerging as platforms for multiband multimode personal communications systems. Radio etiquette is the set of RF bands, air interfaces, protocols, and spatial and temporal patterns that moderate the use of the radio spectrum. Cognitive radio extends the software radio with radio-domain model-based reasoning about such etiquettes. Cognitive radio enhances the flexibility of perso...
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Spatial antenna diversity has been important in improving the radio link between wireless users. Historically, microscopic antenna diversity has been used to reduce the fading seen by a radio receiver, whereas macroscopic diversity provides multiple listening posts to ensure that mobile communication links remain intact over a wide geographic area. In later years, the concepts of spatial diversity...
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Instrumenting the physical world through large networks of wireless sensor nodes, particularly for applications like environmental monitoring of water and soil, requires that these nodes be very small, lightweight, untethered, and unobtrusive. The problem of localization, that is, determining where a given node is physically located in a network, is a challenging one, and yet extremely crucial for...
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An ad hoc mobile network is a collection of mobile nodes that are dynamically and arbitrarily located in such a manner that the interconnections between nodes are capable of changing on a continual basis. In order to facilitate communication within the network, a routing protocol is used to discover routes between nodes. The primary goal of such an ad hoc network routing protocol is correct and ef...
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Configuration of the computing and communications systems found at home and in the workplace is a complex task that currently requires the attention of the user. Researchers have begun to examine computers that would autonomously change their functionality based on observations of who or what was around them. By determining their context, using input from sensor systems distributed throughout the ...
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This article discusses the challenges in computer systems research posed by the emerging field of pervasive computing. It first examines the relationship of this new field to its predecessors: distributed systems and mobile computing. It then identifies four new research thrusts: effective use of smart spaces, invisibility, localized scalability, and masking uneven conditioning. Next, it sketches ...
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A few years ago it was recognized that the vision of a truly low-cost, low-power radio-based cable replacement was feasible. Such a ubiquitous link would provide the basis for portable devices to communicate together in an ad hoc fashion by creating personal area networks which have similar advantages to their office environment counterpart, the local area network. Bluetooth/sup TM/ is an effort b...
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In this article we discuss current and future antenna technology for wireless systems and the improvement that smart and adaptive antenna arrays can provide. We describe standard cellular antennas, smart antennas using fixed beams, and adaptive antennas for base stations, as well as antenna technologies for handsets. We show the potential improvement that these antennas can provide, including rang...
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Piconet is a general-purpose, low-power ad hoc radio network. It provides a base level of connectivity to even the simplest of sensing and computing objects. It is our intention that a full range of portable and embedded devices may make use of this connectivity. This article outlines the Piconet system, under development at the Olivetti and Oracle Research Laboratory (ORL). The authors discuss th...
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This tutorial presents an overview of the Global System for Mobile Communications Short Message Service from the viewpoint of implementing new telematic services. The SMS offers the users of GSM networks the ability to exchange alphanumeric messages up to the limit of 160 characters. The tutorial is motivated by an acute absence of research publications in this field. The information gathered in t...
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Spread spectrum-based code division multiple access (CDMA), has taken on a significant role in cellular and personal communications. We concentrate on direct sequence CDMA (DS/CDMA). We show that there is a natural modification of the present systems that is potentially capable of significant capacity increases. By “natural modification” we mean a modification that can be made conceptu...
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This article provides a detailed discussion of wireless resource and channel allocation schemes. The authors provide a survey of a large number of published papers in the area of fixed, dynamic, and hybrid allocation schemes and compare their trade-offs in terms of complexity and performance. We also investigate these channel allocation schemes based on other factors such as distributed/centralize...
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We present a suite of algorithms for self-organization of wireless sensor networks in which there is a scalably large number of mainly static nodes with highly constrained energy resources. The protocols further support slow mobility by a subset of the nodes, energy-efficient routing, and formation of ad hoc subnetworks for carrying out cooperative signal processing functions among a set of the no...
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Handoff is an essential element of cellular communications. Efficient handoff algorithms are a cost-effective way of enhancing the capacity and QoS of cellular systems. This article presents different aspects of handoff and discusses handoff related features of cellular systems. Several system deployment scenarios that dictate specific handoff requirements are illustrated. An account of handoff-re...
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An adaptive antenna array or a smart antenna is named a software antenna because it can form a desired antenna pattern and adaptively control it if an appropriate set of antenna weights is provided and updated in software. It can be a typical tool for realizing a software radio. An adaptive antenna array can be considered an adaptive filter in the space and time domains for radio communications, s...
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Mobile computers and wireless networks are emerging technologies which promise to make ubiquitous computing a reality. One challenge that must be met in order to truly realize this potential is that of providing mobile clients with ubiquitous access to data. One way (and perhaps the only way) to address these challenges is to provide stationary server machines with a relatively high-bandwidth chan...
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With cellular phones mass-market consumer items, the next frontier is mobile multimedia communications. This situation raises the question of how to perform power control for information sources other than voice. To explore this issue, we use the concepts and mathematics of microeconomics and game theory. In this context, the quality of service of a telephone call is referred to as the “util...
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Wireless networks are being driven by the need for providing network access to mobile or nomadic computing devices. Although the need for wireless access to a network is evident, new problems are inherent in the wireless medium itself. Specifically, the wireless medium introduces new opportunities for eavesdropping on wireless data communications. Anyone with an appropriate wireless receiver can e...
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In this article smart appliances are characterized as devices that are attentive to their environment. We introduce a terminology for situation, sensor data, context, and context-aware applications because it is important to gain a thorough understanding of these concepts to successfully build such artifacts. In the article the relation between a real-world situation and the data read by sensors i...
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Current hardware developments are making mobile computing increasingly attractive. An important class of mobile applications are context-aware applications: applications that change their behaviour according to the user's present context-their location, who they are with, what the time of day is, and so on. This article is about software design for context-aware applications. Currently most such a...
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The authors first discuss the basic cellular digital packet data (CDPD) architecture and its authentication protocols. They then present threats to the network. Next, they investigate the basic requirements of the security architecture and goals in light of attacks. Then they present the improved authentication protocol in operation, and how it deals with faults. Next, they add authenticated key e...
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The design of cellular and microcellular networks is being influenced or changed by the continuous growth in number of subscribers and traffic volume in mobile telecommunications. The author discusses some important aspects of next-generation wireless networks with their implications for teletraffic. Simple models for homogeneous systems, to serve as approximate solutions, are presented. The autho...
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With the emergence of a variety of mobile data services with variable coverage, bandwidth, and handoff strategies, and the need for mobile terminals to roam among these networks, handoff in hybrid data networks has attracted tremendous attention. This article presents an overview of issues related to handoff with particular emphasis on hybrid mobile data networks. Issues are logically divided into...
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Transmitter power control can be used to concurrently achieve several key objectives in wireless networking, including minimizing power consumption and prolonging the battery life of mobile nodes, mitigating interference and increasing the network capacity, and maintaining the required link QoS by adapting to node movements, fluctuating interference, channel impairments, and so on. Moreover, power...
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Next-generation wireless network standards are currently being defined. The access network architectures have several specialized components tailored for their respective wireless link technologies, even though the services provided by these different wireless networks are fairly similar. We propose a homogeneous IP-based network as a common access network for the different wireless technologies. ...
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In its Wireless Initiative, the Information Networking Institute deliberately seeks out innovative wireless and mobile application areas in the expectation that hands-on experience with real applications will keep all research work grounded in reality. Since the beginning of the Initiative three applications have been pursued, each incorporating the concepts of one or more researchers, and each ad...
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This article introduces a sensor information networking architecture, called SINA, that facilitates querying, monitoring, and tasking of sensor networks. SINA serves the role of middleware that abstracts a network of sensor nodes as a collection of massively distributed objects. SINA's execution environment provides a set of configuration and communication primitives that enable scalable and energ...
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This article summarizes the results of the BARWAN project, which focused on enabling truly useful mobile networking across an extremely wide variety of real-world networks and mobile devices. We present the overall architecture, summarize key results, and discuss four broad lessons learned along the way. The architecture enables seamless roaming in a single logical overlay network composed of many...
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We explore various network layer concepts that play a crucial role in the design of mobile networking systems. We show that mobility is essentially an address translation problem and is best resolved at the network layer. We describe services that must be supported at the network layer to carry out the task of address translation. Using these service primitives as building blocks, we describe a ne...
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The PARCTAB system integrates a palm-sized mobile computer into an office network. The PARCTAB project serves as a preliminary testbed for ubiquitous computing, a philosophy originating at Xerox PARC that aims to enrich our computing environment by emphasizing context sensitivity, casual interaction and the spatial arrangement of computers. This article describes the ubiquitous computing philosoph...
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Ad hoc networks have no spatial hierarchy and suffer from frequent link failures which prevent mobile hosts from using traditional routing schemes. Under these conditions, mobile hosts must find routes to destinations without the use of designated routers and also must dynamically adapt the routes to the current link conditions. This article proposes a distributed adaptive routing protocol for fin...
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The process of creating international standards is a mystery to most people, even to the technologists who use them every day. This article describes the origins and processes of the IEEE Project 802.15 Working Group for Wireless Personal Area Networks and their effort to bring standardization to the Bluetooth specification. The committee of experts that comprises P802.15 is chartered with codifyi...
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Starting with today's 3G standards, future-generation wireless networks are discussed. Two complementing major trends are identified: seamless roaming between different air interfaces, leading to the always best connected concept, and the continuous development of the current third-generation standards. The evolution of WCDMA toward high-speed downlink packet access. aiming for peak rates in the o...
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Enabling wireless Internet access is one of the upcoming challenges for mobile radio network operators. The General Packet Radio Service is the packet-switched extension of GSM and was developed to facilitate access to IP-based services compared to existing circuit-switched services provided by GSM. Besides an overview on the basic concept, network architecture, and protocols of GPRS, this article...
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In this article we address the problem of link adaptation in a wireless data system. Link adaptation is necessary in order to match the data rate to time-varying channel and interference conditions. We present a robust radio link protocol (RLP) based on the concept of incremental redundancy (IR). Here, redundant data, for the purpose of error correction, is transmitted only when previously transmi...
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The latest developments and experimentation in mobile ad hoc networks show that MANETs will be an alternative candidate in many private and public multimedia networks. Current interest in MANET systems has grown considerably because they can rapidly and economically extend the boundaries of any terrestrial network; integrating MANET and GSM offers a great number of benefits (e.g., increasing capac...
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This article describes our experiences building a multihop wireless ad hoc network of eight nodes driving around a 700 m by 300 m site. Each node runs the dynamic source routing protocol and interfaces seamlessly with existing Internet infrastructure and the Mobile IP protocol. We present quantitative results from data collected during runs of our testbed under a composite workload including voice...
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The mobile computing environment poses severe problems for Web browsing and Web-based applications. Mobile communication links are typically slow, expensive, and unreliable. This is especially true of wide-area wireless networks, which are becoming increasingly popular. Furthermore, both voluntary and involuntary disconnections from servers are common in the mobile environment, and the standard br...
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The author begins by discussing the background, defining key terms and showing how wireless information systems can be viewed as a natural evolution of computing's relentless march toward greater distribution and ubiquity of access. Next, the research issues faced by designers of wireless information systems are detailed, and some large-scale engineering challenges for such designers are presented...
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As computing technology continues to become increasingly pervasive and ubiquitous, we envision the development of environments that can sense what we are doing and support our daily activities. In this article, we outline our efforts toward building such environments and discuss the importance of a sensing and signal-understanding infrastructure that leads to awareness of what is happening in an e...
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Discusses some typical multimedia applications and services that might be expected to use future wireless and combined wireless/wired networks. These include, among others, multimedia teleconferencing, the electronic newspaper, and nomadic computing. The author then describes control questions to be addressed in the mixed wireless/wired environment and control problems arising in the wireless netw...
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We consider several issues regarding the use of a stratospheric, solar-powered, unmanned aerial vehicle named the Helios Platform (HeliPlat) as a mobile communications base station. This platform is currently being designed at Politecnico di Torino within the HeliNet project funded by the European Commission. The major potential of such a platform as a cellular base station is that it represents a...
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The authors consider a networking environment in which the users are mobile, the topology changes, code division multiple access (CDMA) provides multiple wireless channels, the bandwidth of a given link is unpredictable and possibly very low, the error rates are extremely high and variable, major interference occurs when multiple transmissions take place over (possibly different) links on the same...
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Describes progress in the development of authentication and key agreement (AKA) processes for personal communication systems (PCS). A conceptual framework is first established; this is a three-part general model that characterizes all AKA techniques. Then three proposed AKA methods are compared using this model. These methods are the so-called secret key method of GSM, the secret key method of Uni...
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The SWAP specification for wireless voice and data networking within the home will enable a new class of mobile consumer devices that draw from the power and content of the Internet and the home PC. If cable modems and xDSL represent the “last mile” access to the home, then HomeRFTM's mission with SWAP could be called the “very last 150 feet” within and around th...
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Users of portable computers would like to carry their laptops with them whenever they move from one place to another and yet maintain transparent network access through the wireless link. The existing set of network protocols do not meet this requirement since they were designed under the assumption of a stationary network topology in which hosts do not change their location over time. The authors...
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Software radio has emerged from obscurity to be heralded by some in the personal communications industry as offering a potential solution to man's historical inability to achieve common global standards. In such a scenario reconfigurable terminals, able to adapt to the differing regional radio interfaces, if feasible in the appropriate timescales, appear a very attractive option. In reality, the f...
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